1. Field of the Invention
The present invention relates to a process for producing a heat-sensitive stencil sheet. Specifically, it relates to a process for producing a heat-sensitive stencil sheet, which has a porous substrate layer having a good fiber dispersibility and no adhesive layer resides in.
2. Description of the Prior Art
In a prior art, a heat-sensitive stencil sheet is produced by adhering a thermoplastic resin film on a porous substrate such as a porous thin sheet with an adhesive. For example, one surface of an original and a resin film of a heat-sensitive stencil sheet are brought into contact with each other and irradiated by light from the side of the porous substrate of the heat-sensitive stencil sheet in order to generate heat at the black image portion of the original, thereby the heat-sensitive stencil sheet being engraved either by melting and perforating the film of the heat-sensitive stencil sheet with the aid of the generated heat or by reading the original image by an image sensor and then by melting and perforating the film of the heat-sensitive stencil sheet corresponding to the original image by means of a thermal head. The pictorial property of the printed matter obtained by using such a heat-sensitive stencil sheet is, however, influenced not only by the perforating property of the heat-sensitive stencil sheet but also by the fiber dispersibility in the substrate.
Since an adhesive layer is, however, presented between the film and the substrate in the prior art heat-sensitive stencil sheet described above, there was the disadvantage in that the perforating property is obstructed. It was also difficult from the standpoint of strength to prepare a porous substrate having a low fiber density and a good fiber dispersibility. Furthermore, since the heat-sensitive stencil sheet of the prior art is produced by once preparing a porous substrate and then by laminating a film on the resulting substrate, the process was complicated and there was the problem that the heat-sensitive stencil sheet could not be prepared by using a single production line from beginning to end.